This invention relates generally to vehicle leveling systems and, more particularly, to systems for automatically leveling recreational vehicles.
Recreational vehicles having integral living quarters are well known in the art. Such vehicles provide both transportation and shelter to their owners and occupants. Although a certain amount of movement and motion are expected and tolerated when the vehicle is on the road, such movement is highly undesirable when the vehicle is used as temporary living quarters. Furthermore, comfort and utility can suffer if the vehicle is not substantially level when parked. Because recreational vehicles are frequently parked in remote or rugged areas that are not likely to be perfectly level, various systems and methods have been proposed for securing a recreational vehicle in a level position over non-level terrain.
In one common arrangement, hydraulic jacks are mounted at strategic locations on the recreational vehicle. The jacks extend into contact with the ground and are manually operated so as to bring the vehicle to a level position. Level indicators are sometimes used to help the operator determine when the vehicle is level. This can be a complex, time consuming operation that requires some degree of skill on the part of the operator.
To simplify the leveling process, automatic leveling systems have been proposed. In these systems, an electrical level sensor, which typically consists of a number of mercury switches mounted on a horizontal plate, operates in conjunction with an electronic control circuit to sense which corners of the vehicle are low. The control circuit actuates the jacks as necessary to automatically level the vehicle. Operator involvement is minimal, and leveling can be accomplished relatively quickly.
Despite the advantages of existing automatic leveling systems, many difficulties yet remain. For example, severe strain or torque can be placed on the vehicle frame if a jack lifts one corner of the vehicle before the vehicle is adequately supported at the remaining corners. This tends to twist the entire vehicle causing a variety of problems. For example, doors, cabinets and drawers in the vehicle interior may bind as the vehicle twists. In extreme cases, the vehicle's windshield can be forced from its frame. Such twisting is most likely to occur when the ground is uneven and one jack contacts the ground well before the others.
Another problem with prior leveling systems results if the vehicle is brought to a level condition with only three out of the four jacks actually contacting the ground This can occur, for example, if one of the jacks is located over a depression in the ground and the vehicle is brought to a level condition through the action of the remaining jacks. Although a level attitude is obtained, the vehicle is nevertheless unstable and can tilt, for example, if an occupant moves toward the vehicle's unsupported corner. Again, because the vehicle is not fully supported at all four corners, a twisting force can be imposed on the vehicle frame.
In view of the foregoing, it is a general object of the present invention to provide a new and improved automatic leveling system for recreational vehicles.
It is a further object of the present invention to provide an automatic leveling system that avoids the development of uneven or twisting forces on the vehicle during leveling.
It is a still further object of the present invention to provide an automatic leveling system for recreational vehicles that ensures that all jacks remain in contact with the ground following leveling.
It is a still further object of the present invention to provide an automatic leveling system that ensures vehicle stability following leveling.
It is a still further object of the present invention to provide an automatic leveling system that retracts the jacks without requiring the operator to slide or reach under the vehicle.